High-frequency antenna



June 30, 1953 M. P. MIDDLEMARK 2,644,091

HIGH-FREQUENCY ANTENNA Filed Feb. 26, 1953 all 717%".

- INVENTOR. %w5n.

Patented June 30, 1 953 UNITED STATES PATENT OFFICE HIGH-FREQUENCY ANTENNA Marvin P. Middlemark, Woodside, N. Y.

Application February 26, 1953, Serial No. 338,960

13 Claims. (Cl. 250-3335) called Yagi form which consists of a connected or driven element and several parasitic elements. The parasitic elements generally comprise a number of directors and include a reflector. As is well known, an antenna of the Yagi type is practically operative for only a very narrow band of frequencies so that it is unsuitable for wide band operation.

With the foregoing in mind, I have devised an antenna employing parasitic elements, either in simple or Yagi form, which is of wide band operation and which will exhibit high gain over such band. The antenna is further of unusually sturdy construction, thi aspect having not only mechanical advantages but insuring stability of operation over long periods of time and under varying conditions.

The antenna of the instant invention, in one embodiment, is realized by so forming a single blank of material that various parasitic antenna lengths of the proper spacing are inherently found in the structure, such blank serving as a unitary, multi-frequency parasitic device.

In a more advanced from of the antenna, a metal blank is so cut that it presents various effective transverse parasitic lengths properly spaced according to the frequency they represent and providing a series of such parasitic elements for each frequency served. Accordingly, the antenna serves to provide a plurality of parasitic elements in a wide band system so as to achieve the high gain characteristics of Yagi antennas for each frequency served by the single antenna.

The invention will be further understood from the following description and drawings in which:

Figure 1 is a top plan view of a simple antenna system constructed according to the instant invention Figure 2 is a modification of the side contours of the parasitic plate so as to achieve varied spacing with regard to different frequency portions thereof;

megacycles. plate I2 will define the linear portion of the plate which serves as a parasitic element at about 750 megacycles. Accordingly, every frequency in the i band will be provided with an effective parasitic element by the single plate I2.- I

. 2 Figure 3 is a view similar to Figure 2 with different side contours of the plate;

Figure 4 has a top plan View of a complex form-f of antenna constructed according to the instant invention;

Figure 5 is a side elevational view of the antenna shown in Figure 4; and

Figure 6 is a modified embodiment of the simplified form of antenna.

The simplified form of antenna disclosed in Figure 1 shows a driven element [0 secured to an insulated cross beam I-l. Driven element l0, although it may comprise a simple dipole, is

preferably, but not necessarily, of broad band form such as a conicaL fan or so-called bow-tie antenna construction.

A parasitic element, whether a director or a reflector, is conventionally disposed adjacent to The parasitic inherently the driven element. narrows the band Width, the greater the number of parasitics, the narrower the band. In the simplified form shown in Figure 1, I dispose a plate [2 adjacent to the driven dipole [0. Plate [2 is of triangular form although its apex is truncated along the front edge [3, such front edge being spaced from the dipole I0 pursuant to conventional spacings for parasitics. The

plate I2 is illustrated as being a solid sheet but .15 wave length. The highest frequency is repre- 1 sented by the length of front edge 13 while the lowest frequency isrepresented by the length of the rear edge I4. -It will be noted that edge [3 is closer to dipole- I0 than is edge [4 although I they are both spaced approximately .15 Wave length for their corresponding frequencies.

It has been found that plate l2 exhibits the property of providing an effective parasitic length at any frequency between the frequencies represented by edges I3 and 14. Thus, assume that the dipole I0 is of a length to resonate at 500 megacycles, this being a frequency near the lower end of the band served. Edge l3 may represent 890 megacycles while edge l4 may-represent 470 An imaginary line 15 across the When the driven element It) is in a single vertical plane, the edges [3 and I4 are parallel thereto, while the inclined side edges [6 and ll of the substantially triangularly-shaped plate provide automatic and uniform increased spacing with increased effective parasitic lengths.

The parasitic plate I8 shown in Figure 2, varies the effective spacing of a parasitic linear portion of the plate from the driven dipole by providing a decreased spacing from the driven dipole in respect to lower frequencies. This is accomplished by forming the side edges I9 and of convex form. The parasitic plate 2| shown in Figure 3 produces the opposite effect since the side edges 22 and 23 are concave.

I have further devised a more advanced parasitic system which follows the Yagiform above described. directors and at least one reflector are generally included in order to achieve the high gain characteristics of such antennas. As above stated, increasing the number of parasitic elements normally greatly narrows the band width. This limitation is corrected by the antenna disclosed in Figure 4.

.In Figure 4, the driven dipole 25 is disposed between plates 26 and 21. Plate 26 is, as will be; more fully described hereinafter, a reflector plate functioning as does plate l2 in Figure 1.

Plate 21, however, effectively provides a series of director elements at any frequency in the band of frequencies served. Thus, at any one such frequency, the effective picture of a Yagi antenna is achieved.

Plate 21 is unitary and has a plurality of laterally extending arms radiating therefrom. Each arm is of, truncated triangular form with the top and bottom edges of the truncated triangle parallel to the driven dipole 25. The apical portion of each arm isnear its top edge and all the apical portions face in the same direction, 1. e. toward thedipole 25. The leading edge 28 of plate 21 constitutes the first parasitic element of the highest frequency served, this edge 28 being the top or front edge of the first arm 29.

The second arm 30 provides the second parasitic element along the linear portion 3|, such linear portion being of the same width as edge 28 as indicated by the guide lines 32 and 33. The third arm 34 provides a third parasitic element along the line- 35 thereof. Accordingly, three parasitic elements are effectively provided, one by eachof thev triangularly-shaped integral arms. The spacing between the driven dipole 25 and the first parasitic element, 1. e. edge 28 is of the order of .1 of a wavelength at the frequency represented by such parasitic element. The same spacing exists between the first and second elements while the third element is preferably spaced to a greater degree, that is .15 wave length.

The lowest frequency served is represented by the bases of the triangular arms, i. e. linear portions 36, 31 and 38. These too are spaced from the driven dipole .1, .1 and .15 wave lengths respectively at such lowest frequency. Intermediate frequencies along the axis of the substantially triangular arms are likewise accommodated. For example, linear portions 39, and

4| represent an intermediate frequency so that the parasitic elements provided thereby are properly spaced.

It will be recognized from the description of Figure 5 that a plurality or series of parasitic elements are provided, in the single structure shown so as to avoid the heretofore limitations- In such an antenna, a number of' are cancelled out by plate widths appearing on the respective sides of the desired or resonant transverse linear portions. The expedient of forming the triangular arms of varying breadths (by breadths I mean the distance between the base Of the triangle and the truncated apex) I can effectively vary the spacing of the elements from each other as above described. Inasmuch as the radiating. arms are spaced so as to serve as directors, the maximum signal reception is in p the direction of such directors.

In addition to providing the directors in the antenna of Figure 5, I further provide a reflector plate 26 which follows the form of the plate.

shown in Figure 1. The spacing betweenthe driven element 25 and the leading edge 42 of the reflector plate 26will be in the order of .15

to .25 wave length as determined by'the length of edge 42 as will be recognized. Edge 43 represents the lowest frequency to be served and it is accordingly spaced further away from the driven dipole. Intermediate frequencies are provided along the breadth of the plate. It will be recognized from this description that the antenna of Figure 4 provides a five element Yagi with three directors and one reflector over a wide band of frequencies. It is further possible to add elements by increasing the number of arms, either on the reflector or director side.

In Figure 6 is disclosed a modified embodiment where a reflector or director plate according to the instant invention is substituted by a series of spines or rods 44. Only onev of such spines or rods will act as a parasitic element at one frequency because of the length and. spacing of such rods from the driven dipole 45. The. length of dipole 45 is an intermediate frequency near the lower frequency end of the band to be served. When the rods serve as directors, the spacing between dipole 45 and the first rod will be .1 to .15 wave length while .as reflectors, the spacing will be approximately .15 to .25 wave length. It will. be observed that, in accordance with the principles of this invention, the length of each rod or transverse linear portion. and its spacing from the driven dipole are correlated. The longer the rod, the. greater the spacing.

In any of the above embodiments, there is disclosed a simple system of achieving high gain by the use of parasitic elements automatically independently operative over a wide band of frequencies and without requiring any Variation in the length of the plate or the parasitic elements provided thereby. The parasitic plates have been illustrated as being in horizontal planes but they may be disposed vertically or' trated may be of multiple or stacked form pur suant to conventional practice.

In addition, two parasitic plates may be What is claimed is:

1. A high frequency antenna comprising a driven element and a parasitic system therefor, said parasitic system being planar and comprising at least one graduated series of transverse linear portions, each portion varying in its effective transverse dimension relative to the other portions of the series, said driven element lying in the same plane as said series of linear portions.

2. A high frequency antenna comprising a driven element and a parasitic member spaced therefrom, said parasitic member comprising a planar, truncated triangular plate, the truncated edge of the plate facing said driven element, said driven element lying in the plane of said plate.

3. A high frequency antenna comprising a driven element and a series of parasitic arms, each of said arms comprising a graduated series of transverse linear portions, each portion varying gradually and uniformly in its effective transverse dimension relative to the other portions of the series, each of said arms being planar and all being in the same plane, said driven element lying in the same plane as said arms.

4. A high frequency antenna comprising a driven element and a parasitic member disposed adjacent thereto, said parasitic member comprising an integral series of truncated triangular arms each having their bases substantially parallel to said driven element and in the same plane therewith.

5. A high frequency antenna comprising a driven element and a parasitic member disposed adjacent thereto, said parasitic member comprising an integral series of truncated triangular arms, each arm having its base parallel to said driven element, the truncated edge of each arm being parallel to said base and being spaced closer to said driven element than said base, all of said arms being planar and the driven element lying in the same plane as all of said arms.

6. A high frequency antenna comprising a driven element and a planar plate spaced therefrom, said plate being formed with a series of laterally radiating arms along the sides thereof, the driven element lying in the same plane as all of said arms.

7. A high frequency antenna comprising a driven element and a parasitic member disposed adjacent thereto, said parasitic member comprising an integral series of truncated triangular, laterally radiating arms, each arm having its base parallel to said driven element, at least one of said arms being narrower in its breadth along the length of said parasitic member than another arm in said series.

8. A parasitic member for use in high frequency antenna, said parasitic member comprising a planar plate having a series of laterally extending arms along the sides of the plate, each of said arms being substantially triangular, aligned, and truncated at the apex and at least one of said arms being of a breadth from the base thereof to the truncated apex which is greater than the corresponding breadth of another arm in the series.

9. A high frequency antenna comprising a driven element and a parasitic system therefor, said parasitic system being planar and comprising at least one graduated series of transverse linear portions, each portion varying in its effective transverse dimension relative to the other portions of the series, said driven element lying in the same plane as said series of linear portions,

the foremost of said linear portions and which is closest to said driven element having the smallest transverse dimension and the series graduating so that the last linear portion and which is furthest from said driven element has the greatest transverse dimension.

10. A high frequency antenna comprising a driven element and parasitic members on both sides thereof and spaced therefrom, each of said parasitic members comprising at least one planar, truncated triangular arm the base of which is parallel to said driven element, and the driven element and both parasitic members being all on substantially the same plane.

11. A parasitic member for use in a high frequency antenna, said parasitic member comprising an integral series of truncated triangular arms disposed successively along the length of the parasitic member, the apical portions of each arm extending in the same direction.

12. A high frequency antenna comprising a driven element and a parasitic member spaced therefrom, said parasitic member comprising a truncated triangular, planar plate, the base of which is parallel to said driven element and the sides of which are convex, said driven element lying in the plane of said plate and the truncated edge of the plate facing said driven element.

13. A high frequency antenna comprising a driven element and a parasitic member spaced therefrom, said parasitic member comprising a truncated triangular, planar plate, the base of which is parallel to said driven element and the sides of which are concave, said driven element lying in the plane of said plate and the truncated edge of the plate facing said driven element.

MARVIN P. MIDDLEMARK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,192,532 Katzin Mar. 5, 1940 2,434,893 Alford et a1. Jan. 2'7, 1948 2,604,595 Clark July 22, 1952 

